In the related art, as described in PTL 1, a switching valve is known that is to be mounted onto a mounting surface of a manifold base by using mounting screws in such a manner as that a plurality of the switching valves are arranged in a row. The switching valve has ridge portions and grooves, which are formed on and in side surfaces of a body having a sliding hole, and insertion holes that are formed along the ridge portions and through which the mounting screws are to be inserted.
The ridge portions and the grooves extend in a top-bottom direction with respect to the mounting surface of the manifold base and are each formed so as to have a semicircular cross section, the diameter of the cross section of each of the ridge portions and the diameter of the cross section of each of the grooves being approximately the same as each other. Accordingly, positioning of the switching valve can be performed by inserting the ridge portions of the switching valve into the grooves of one of the other switching valves that is adjacent to the switching valve. In addition, the plurality of switching valves can be efficiently mounted onto the manifold base by inserting screws or vises (hereinafter referred to as screws or the like) through the insertion holes so that the switching valves are screwed onto the manifold base.
However, in the switching valve described in PTL 1, the outer diameter of the sliding hole is determined in accordance with the distance from the axis of the sliding hole to the bottom of each of the grooves, and thus, it cannot be said that the thickness between a mounting hole and the sliding hole is efficiently utilized.
On the other hand, there is a need for this type of switching valve to be reduced in size and to have a large flow rate, and thus, it is desirable that the hole diameter of a sliding hole be efficiently increased with respect to the width of a body.